1. Field of the Invention
The invention generally relates to a package structure and a fabricating method thereof, and more particularly, to a package and the carrier structure thereof and a fabricating method thereof with demand on high heat conduction performing.
2. Description of Related Art
The purpose of chip package is to provide a chip with an appropriate signal path, a heat conduction path and structure protection. The traditional wire bonding technique usually adopts a leadframe as a carrier of the chip. Along with gradually increasing the bonding point density of a chip, the leadframe is unable to provide a higher bonding point density, so that it is replaced by a package substrate with high bonding point density, where the chip is packed onto the package substrate through conductive media such as metal wires or bumps.
In general speaking, an adhesive layer conformed to the chip would be disposed between the chip and the package substrate. The chip is fixed on the package substrate through the adhesive layer. The heat produced by the chip would be transferred to the package substrate through the adhesive layer so as to conduct heat. When paste, for example a silver epoxy, is used as the material of the adhesive layer, due to the poor thermal conducting rate (less than 20 W/mK), high coefficient of thermal expansion (CTE) (greater than 30 ppm/K) and poor adhering strength of the silver epoxy, so that when the heat produced by the chip is transferred to the package substrate through the adhesive layer, an increasing thermal resistance is caused by the adhesive layer, which further leads to poor heat conduction and decrease the strength of the adhesive layer and even destroy the adhesive layer when thermal stress occurs. Hence, how to make the heat produced by the chip more efficiently transferred to outside has become one of development tasks for the designers.